This invention relates to an electronic musical instrument that performs an automatic accompaniment by detecting a chord corresponding to a played sound.
Various kinds of electronic musical instruments which performs an automatic accompaniment by detecting a chord corresponding to a pressed key or keys have been developed. In this kind of musical instrument, a key region is generally divided into lower and upper registers and the chord is detected based on the key or keys which are pressed in the lower register.
The following two modes are generally used as chord detection modes. In the first mode (FC mode), a chord is determined based on all keys which are pressed in the lower register; in the second mode (SF mode), the chord is detected according to the key having the highest pitch among the key or keys pressed in the lower register, the type of chord (major, minor, seventh, etc.) is detected according to the combination of white and black keys pressed below the highest pitch sound key.
The latter SF mode is an abbreviated mode for beginners that determines an appropriate chord type. For example, the chord is major when only white keys are pressed below the most treble sound key, minor when only black keys are pressed, and a seventh when both white and black keys are pressed.
In FC mode, it is necessary to press keys that correspond to the notes constituting the chord to generate the desired chord, thus making performance difficult.
Also, in SF mode, the sound of the pressed key differs from the type of chord to be played because chord detection is based on the combination of keys pressed. As a result, performance in the upper and lower registers does not have the same feeling.
An electronic musical instrument, in which an abbreviated pattern for detection corresponding to a chord is memorized, is known. When the keys pressed match the abbreviated pattern, the electronic musical instrument generates a formal chord corresponding to the keys (Japanese Patent Application, Laid-Open Publication No. Sho. 59-174894). A similar incongruity, as in the case of SF mode, results even in this device from the fact that an actually generated sound has no direct relation with the depressed key or keys.